The present technology relates to polymer material blends, products containing such blends that are manufactured for the electrical utility market, and methods of manufacturing such products. In particular, the polymer material blends described herein can be cross-linked polyolefin blends that, upon molding, have characteristics compatible with the requirements of electrical utility products. Insulator products that can find application with the polymer material blends described herein can be from a number of electrical insulator devices including, but are not limited to, vise-top insulators; pin insulators; line post insulators; F-neck, C-neck, and J-neck pin insulators of classes ANSI 55-3, 55-4, and 55-5; Spacer cable spacers, Brackets, hangers, Line post sensors, cable restraint insulators, and vertically mounted or horizontally mounted transmission products.
Thermoplastic materials have been used in the electrical industry for many years, such as in 15 kV pin type polymeric insulators, which were introduced in 1969. Since that time additional insulators have been added, such as in the 25 kV and 35 kV categories. Vise-tops insulators, which include an integral cable clamp, were added to each voltage category some time later. The thermoplastic material presently used to produce the insulators is a high-density polyethylene (HDPE). Stabilizers are incorporated in optimum percentages to maintain the original electrical and mechanical properties for the lifetime of the product as it is exposed to the environment, in particular ultraviolet (UV) light, and electrical stress from the energized cables and system. The stabilizers also impart other properties such as track and UV resistance. The final blended material possesses electrical and mechanical characteristics sufficient for the intended application. However, the typical HDPE material has a temperature limitation at/below 120° C.
Insulators utilized in overhead electrical applications to isolate electrical cables from ground are required to meet all performance criteria of the applicable ANSI C 29.1 specification, the disclosure of which is hereby incorporated by reference in its entirety. It also is required to meet requirements of tracking and UV Resistance. As population densities, manufacturing and other service industries have grown, utilities have been required to carry heavier current loads resulting in hotter conductors. Polyurethane insulators are typically used in such applications since currently utilized HDPE materials cannot meet such thermal conditions.
Therefore, under present electrical transmission requirements, there exists a need for materials and electrical transmission products that can withstand conductor temperatures in excess of 120° C. without weakening or loss of structure and performance.